Doomsday isn't going to happen tommorrow, but if you think its a possibility then it makes sense to sink money into a minature fortress now, then later as thing

Doomsday isn't going to happen tommorrow, but if you think its a possibility then it makes sense to sink money into a minature fortress now, then later as things worsen, grow outwards and invest in lesser protected zones for people who are aligned with you to join.